Telephone system.



Patented Dec. 8. 1914.

UNITED STATES PATENT OFFICF.

WILLIAM w. DEAN, 0F ELYRYIA, omo, ASSIGNOB. BY MESNE ASSIGNMENTS, TO THE GARFORD MANUFACTURING COMPANY. or ELYRIA, OHIO, A CORPORATION or OHIO.

I TELEPHONE SYSTEM.

5 a telephone system in which it will be impossible for the operator, through accident or otherwise, to connect the ringing genera.- tor in circuit with a busy line.

In the use of telephone systems generally in the past, especially in connection with multiple switchboards, it has been possible for connection to be made by means of one of the multiple jacks with two connected lines when these .lines were connected through other jacks and suitably connecting circuits for conversation, and it has been possible by the extra connection thus made to send ringing current out on to the busy line with the. result that often serious injury has been done to the persons using the telephones.

It is an object of my invention to so connect the apparatus at the exchange that it will be impossible to complete a circuit from the ringing generator through the connecting apparatus to a line which is in talking condition or, as it is commonly called, busy.

My invention consists in equipping one of the relays of each of the cord circuits used for connecting the lines for converse-- tion with extra. contacts through which the generator circuit is closed- These relays are so 'associa ted with the calling plugs of the cord pair that when one of said plugs is inserted in a jack connected to a busy line, the relay is energized and connection between these extra contacts is broken, thus interrupting the connection of the ringing generator to that particular cord pair. An-

other result secured by my invention is that when a cord pair is used for connecting two subscribers for conversation and the connection is complete with the exception that the called subscriber has not responded, the operator may ring the desired substation until such subscriber docs respond, but as soon as' he removes his receiver from the Specification of Letters Patent.

Patented Dec. 8, 1914.

Application filed March 12, 1908. Serial No. 420,546.

switch hook a relay connected with the cord pair is energized and by means of contacts controlled thereby the circuit from the ringinggenerator to such cord pair is broken and thus the operator is prevented from again sending ringing current throu h the apparatus at the substation connecte with the calling plug. I

Referring to the drawings, I have shown two party lines extending by their limbs 1, 9 and 3, 4 from a plurality of'substations A, A, A A and C, C, C", C to multiple jacks J, J and J J 3 at an exchange. These line circuits are identical, as are the substations connected therewith, and hence detailed description of but one circuit and one substation is needed. p

The line wires 1, 2 are connected to armatures a6 and 57 of cut-ofl? relay R and connection is normally made through such arm'atures by contacts 58 and 59, through line relay R and wires and 51 with the terminals of'the main battery B. The-relay R is provided with an armature '66, adapted when attracted to close the contact 67 and thus to complete a circuit between wires 50 and 51 through line lamp 68. Armatures-56 and 57 are adapted to beoperated by relay R, one termiral of which is connected by wire 69 with the rings 60 and 61 of jacks J and J, while the other terminal of the winding of this relay R is connected by wire 51 with the grounded terminal of battery B.

The substation A is equipped with the transmitter 13 connected through the usual hook switch with line wire 1' and with the terminal of this transmitter is connected the juncture of windings 14: and 16, which are two windings of a l Vheatstone bridge arrangement used for supplying current to the receiver 18. This \Vheatstone bridge consists of the inductive windings 1G and 17 and the non-inductive windings 14 and 15, so connected and of such resistance that the receiver 18 is connected in bridge between the points of juncture of the windings 15 and 16 and 1.4 and 17, which points are of equal potential, when direct current flows from the transmitter 13 through these connected windings and back to line wire 2. As a result of the impedance value of the windings 1G and 17, however, when voice currents flow through this same circuit the are practically all directed through the re ceiver 18. A ringer 12 in circuit with condenser 11 is also provided in bridge of the line wires 1 and 2.

As a result of the construction described above, when. the receiver is removed from the switch hook at the substation A, the relay .R' is energized, current taking the fol lowing path: battery B, wire 50, relay R, contact 58, armature 56, wire 1, transmitter 13, thence through the bridge windings back to wire 2, armature 57, contact 59, wire 51, to battery B, as result of which the relay R is energized and a circuit closed through the. line-lamp 68, as followsz'battery B, w re 50, armature 66, contact 67, lamp68, wire 51, back to the battery B. In response to this signal. an answering plug of the cord pair is inserted in .the answering jack with the result that precisely the same operation takes place as illustrated for the calling plug P, which is as follows:' The sleeve relay S connected with the plug is energized by the following circuit: .batte'ry B, wire 50, wire 43, wire 45, relay S, wire 44, cord strand 6,sleeve 63 of the plug P, ring 60, wire 69, relay R, wire 51, back to battery B. As result of this the relayR is ener gizcd and armatures 56 and 57 are removed from contacts 58 and 59, respectively, cutting ofi connection between the battery B and line wires 1 and 2. The several ringers located at-the different substations may be of any well known type adaptive to selective signaling, that form of ringer known as the harmonic ringer-be ng particularly available for this purpose.

The cord circuit shown for connecting lines for conversation consists of tip and sleeve strands 5, 7, 9 and 6, 8, 10, respectively, terminating in answering and calling plugs P and P. Strands 5, 6 terminate in tip and sleeve 62 and 63 respectively, of calling plug P, while the strands 9, 1O terminate similarly at the answering plug P Besides the relay S associated with the sleeve strand as above described, there is a second relay T associated with the tip strand, the two relays cooperating to eflfect the supervisory signaling 'for the calling plug. Similar relays are associated with the tip and sleeve strands of the answering plug, but since the supervision of the connection is not a feature of this invention, no reference is made to the signaling relays except in so far as they are concerned in the control of the circuits forming the subject matter of this invention. When the relay S is energized as described above by the plug P being inserted in the jack J,'a signalingcircuit is closed as follows: battery B, wire 50, wire 43, wire 45, contact 35, armature .34, wire 48, contact 37, armature 36, supervisory lamp 38, wire 41, wire 42, back to battery B. The relay also closes a second circuit as follows:

from the tip strand 7 through wire 39, armature 32, contact 33, relay '1, wire 41, wire 42 to the grounded terminal of battery 13,. as result of which when the line wire 2,

which is at this time connected to the cord strand 7, is connected with the live side of the battery, the relay T will be energized.

This is accomplished when the receiver is removed from the switch hook atone of the substations, current taking the following.

path: battery B, wire 50, wire 43, wire 45,

relay S, Wire 44, cord strand 6, sleeve 63, 8

contact spring 53, line wire 1, transmitter 13, line wire 2, jack spring 52, tip 62, cord strand 5, key spring k, contact 25, cord strand 7, wire 39, armature 32, contact 33, wire 40, relay T, wire 41, wire 42, back to battery B. This attractsarmatures 36 and with the ringing generators G, G, G G,

adapted to selectively ring the several substations connected to the different lines The ringing keys It, It, It? and k are me I chanically connected by meansnot shown, with the key springs in and k so that when operated to put ringing current-on to the line the cord strands are opened to prevent the ringing current flowing back into the answering end of the cord. Assumingthat current from the generator G is adapt-Y ed to operate the ringer 12, the-ringing key lcis operated, and if the receiver 18 has not been removed fromthe switch hook a circuit would be completed as follows: ringing generator. G, contact 22, spring is, wirev 20, contact 31, armature v29, wire 49, cord strand 5, tip 62, jack spring 52, line wire 2,

condenser 11, ringer 12, line wire 1, jack spring 53, sleeve 63, ring 60, wire 69, relay R, wire 51, ground 9, ground 9, back to generator G. From the circuit just traced it appears that when relay T is energized the connection ofthe ringing generator to the cord circuit is interrupted and that the operation of the keys is, k, k, [a will not produce any effect upon the cord circuit or the line with which-the cord circuit may be connected. When the relay T is energized the armature 29 engages contact 30, establishing a connection between cord strands 5 and 7, which connection effects the holding of the relay T if one of the ringingkeys is energized while the line connected with the calling plug is busy. This circuit is traced as follows: battery B, wire 50, wire 43, wire 45, relay S, wire 44, sleeve strand 6, sleeve 63, jack spring 53, line wire 1, transmitter 13, line wire 2, jack spring52, tip

spects, and this cord circuit is represented as connected with the line 1, 2, which, as described above, is represented as busy. Whether the answering plug I of the lower cord circuit is in an answering jack of some other line or whether it is entirely disconnected is immaterial to the operation of the relay T which is immediately energized upon the insertion of the plug P into the jack J connected with the busy line 1, 2. This energizing circuit may be traced as follows: battery B, wire 50, wire t5, relay S, wire 44*, cord strand (3 sleeve 65, jack spring 55, line wire 1. transmitter 13. line wire 2, jack spring 5 tip (ll, cord strand 5", key spring is, contact 25, cord strand 7 wire 39 armature 32, contact 33, wire -10, relay T, wire 41, wire 42, back to battery B.

After being energized, the relay T is held against release by the opening of the key is, by means of a circuit as already described, which is identical with that shown for the cord circuit in the upper part of the drawings. The ringing key It is shown as operated in the lower cord circuit, but as result of the operation of the armature 29 the circuit is interrupted between armature 29 and contact 31, and hence connection between the generator G and the tip 64: is interrupted and ringing current can not be sent from the generator (lr to any of the substations connected with the line 1, 2. Since keys a, I. are all connected through the same circuit by wire 20 to the tip (34, it will be understood that the operation of the relay T serves in similar manner to effectually disconnect all of the ringing generators from the calling plug. By this means I have made it impossible for an operator to send ringing current out on a busy line, and l have thus made it impossible to send ringing current through the receiver at any oi' the substations where such receiver is being used.

Among the desirable results of my invention may be mentioned the elimination of injury to the subscribens car due to the ringing current in the receiver and also the elimination of a pargc part of the danger due to high tension signaling currents being applied to telephone instruments while the subscriber is in proximity to the connections and liable to receive a shock from such current through careless handling of the telephone connections.

\Vhile I have shown my invention in the particular embodiment herein disclosed, I do not limit myself to this modification, but claim broadly any equivalent construction for securing the same results.

'hat I claim is 17 In a telephone system, aplurality of lines extending by their limbs from substations to an exchange, switching mechanism at the exchange having an answering and a alling end for connecting suclrlines for conversation. a. source of signaling current at the exchange, switch contacts and circuit connection for connecting said source to said system, contacts in said switching mechanism between the answering end and the circuit connections of the source of signaling current. means for preventing the sending of signaling current from such source to a bin alraidy in talking communication,

iiiid a circuit independent of said last named contacts for locking said means.

2. In a telephone system, a plurality of lines extending by their limbs from substations to an exchange, switching mechanism at the exchange having an answering and a calling end or connecting such lines for conversation, a source of signaling current at the exchange, switch contacts and circuit connections for connecting said source to said system, contacts in said switching mechanism between the answering end and the circuit connections of the source of signaling current, a relay for preventing the sending of signaling current from such source to a line already in talking communication, and a circuit independent of said last named contacts for locking said relay.

3. In a telephone system, a plurality of lines extending by their limbs from substations to an exchange, a cord circuit at the exchange for connecting said lines together, a source of signaling current at the exchange, circuit connections and switch contacts for connecting said source to the system, a switch adapted to sever said cord circuit when the signaling current is connected to said system, means for preventing the sending of signaling current from said source to a line already in talking communication, and a locking circuit for said preventive means independent of said switch.

4. In a telephone system, a plurality of lines extending by their limbs from substations to an exchange. a cord circuit at the exchange for connecting said lines together, a source of signaling current at the exchange, circuit connections and switch contacts for connecting said source to the system, a witch adaptcd to sever said cord circuit when the signaling current is (Eonnected to said system, a relay for preventing the sending of signaling current from said source to a line already in talking communication, and a locking circuit for said relay independent of said switch.

5. In a telephone system, the combination with a cord circuit, of a ringing key therefor, a subscriber controlled supervisory relay, said ringing key being connected with a strand of the cord circuit through normal contacts of said supervisory relay, substantially as described.

6. In a telephone system, the combination with a cord circuit, of a ringing key there for having a plurality of contacts normally in series with a portion of a talking strand of the cord circuit, a subscriber controlled supervisory relay having contacts in the circuit of said key, said relay being actuated during conversat'ron to disconnect said series.

key contacts from the talking circuit.

7. In a telephone system, the combination with a cord circuit, a ringing generator, a subscriber controlled supervisory relay, the current from said generator being connected with the calling end of the cord circuit through normally closed contacts of said relay.

8. In a telephone system, the combination of a main station, a plurality of substations and subscribers lines connecting the substations and main station, a cord circuit at the main station'for connecting subscribers lines together, means including plugs and jacks for connecting the cord and lines together, said cord including two strands. one connected to the tips of the plugs and another to the sleeves of the plugs, a subscriber .controlled relay connected to the tip strand of said cord, a source of ringing current, a ringing key controlling the same, said ringing key being connected with a strand of the cord circuit through normal contacts of said supervisory relay.

9. In a telephone system, the combination with a main station, a plurality of substations, telephone lines connecting the substations to the main station, a cord circuit at the main station for connecting said lines together, switching means including plugs and jacks for connecting the cord to said lines, one of the strands of the cord circuit being connected to the tips of the plugs, a source of ringing current, a ringing key controlling the same, said ringing key having a plurality of contacts normally in series with a portion of a talking strand of the cord circuit, a supervisory relay connected.to the tip strand of the cord circuit and having contacts in the circuit of. said key, said relay being actuated during conversation to disconnect said series key contacts from the talking circuit, substantially as described.

10. In a telephone system, a plurality of switching said substation,

' mechanism telephone lines extending by their limbs from sub-stations to an exchange, switching mechanism at the exchange for connecting such lines for conversation, a supervisory relay in such exchange switching mechanism, a source of current at said exchange for signaling the sub-stations, circuit connections for connecting said source to said telephone lines, contacts in said circuit connections directly controlled by said supervisory relay and operated when the sWitching mechanism is connected to a busy line to automatically prevent the connection of the source of ringing current to said busy line.

11. In a telephone system, a plurality of telephone lines extending by their limbs from sub-stations to an exchange, switching mechanism at the exchange for connecting such lines for conversation, supervisory mcans in such exchange switching mechanism, a source of current at the exchange for signaling the sub-stations, circuit connections for connecting said source to said telephone lines, contacts in said connections directly controlled by said supervisory means and operated when the switching mechanism is connected to a busy line to prevent the connection of the source of ring ing current to said busy line.

12. In a telephone system, a plurality of telephone lines extending by their limbs from substations to an exchange, switching mechanism for connecting said lines, a source of signaling current for signaling said substations, a ringing key controlling the source of signaling current, circuit connections therefor normally connected to said connections, and supervisory means operating on connection of the switching mechanism to a busy line to automatically disconnect the source of signaling cuiient.

13. In a telephone system, a plurality of telephone lines extending by their limbs from substations to an exchange, switching source of signaling current for signaling a ringing key controlling the source of signaling current, circuit connections therefor normally connected to said switching connections, and supervisory means operating on connection of the switching mechanism to a busy line to automatically disconnect the source of signaling current and prevent the application of signal ing current to a line already in talking condition.

14. In a telephone system, a plurality of telephone ines extending by their limbs from substations to an exchange, switching for connecting said lines, a source of signaling current for signaling said sub-stations, a ringing key for said source normally connected to said switching the cord and to mechanism. and supervisory means operated on connection of the switching mechanism with a busy line to automatically disconnect the source of ringing current.

13. In a telephone system, a plurality of telephone lines extending by their limbs from substations to an exchange, switching mechanism for connecting said lines, a source of signaling current for signaling said substations, a ringing key for said source normally connected to said switching mechanism, and suymrvisory means operated on connection of the switching mechanism with a busy line to automatically disconnect the source of ringing current, and prevent the application of signaling current to a line already in talking condition.

16. In a telephone system, a plurality of lines extending by their limbs from subscribers stations to an exchange, a cord circuit at the exchange for connecting the lines, a source of signaling current at the exchange, a ringing key for connecting said source to the cord circuit, said springs normally connected to said cord circuit, a relay in said cord circuit adapted to be automatically operated when the cord is connected to a busy line to disconnect said normal connection between the switch springs and prevent application of the signaling current to a line already in talking condition.

17. In a telephone system, a plurality of telephone lines extending by their limbs from substations to an exchange, switching mechanisms at the exchange for connecting the lines for conversation, a signaling circuit adapted to be manually connected to such switching mechanisms, and means for preventing the closure manually of such signaling circuit to one of such switching mechanisms when such switching mechanism is connected to a busy line.

13. In a telephone system, a plurality of telephone lines extending by their limbs from substations to an exchange, switching mechanisms at the exchange for connecting the lines for conversation, a signaling circuit adapted to be manually connected to such switching mechanisms, means for manually controlling the signaling circuit when the switching mechanism is connected to one of the lines in signaling condition, and means for preventing the closure manually ot the signaling circuit when such line is in talking condition.

19. In a telephone system, a plurality of tele hone lines extending by their limbs from substat ons to an exchange, cord circuits at the exchange for connecting the lines for conversation. a signaling circuit adapted to be manually connected to such cord circuits, and independent means adapted to control the continuity of such signaling .circuit, one of such means under the control of an exchange operator to connect the signaling circuit to a cord circuit con nccted in signaling condition to one of the lines. and another of such controlling means under the control of the substation connected to such line.

20. In a telephone system, a telephone lines extending by from substations to an cuits at the exchange for connecting the lines for conversation, a signaling circuit adapted to be manually connected to such cord circuits, a key associated with each of such cord circuits by which an exchange operator may complete the signaling circuit to the corresponding cord circuit after such cord circuit has been connected with one of the lines in ringing condition, and means for preventing the closure of the signaling circuit by means of such key when such line is placed in talking condition.

21. In a telephone system, a plurality of telephone lines extending by their limbs from substations to an exchange, cord circuits at the exchange for connecting the lines for conversation, a signaling circuit adapted to be manually connected to such cord circuits, a key associated with each of such cord circuits by which an exchange operator may complete the signaling circuit to the corresponding cord circuit after such cord circuit has been connected with one of the lines in ringing condition, and means for rendering such key inoperative when such cord is connected to a busy line.

22. In a telephone system, a plurality of telephone lines, a central station circuit adapted to connect said lines in circuit, a source of signaling current adapted to be connected to operate the signal at substations on said lines, circuit connections for connecting said source in circuit with said telephone line, means to prevent the connection of said source with a busy line, and a manual switch to connect the said source to the said circuit connections, said manual switch being independent of the preventing means.

23. In a telephone system, a plurality of telephone lines extending by their limbs from substations to an exchange, cord circuits at the exchange for connecting the lines for conversation, a signaling circuit adapted to be manually connected to such cord circuits, manual means associated with each of such cord circuits for controlling the continuity of the signaling circuit thereto, and a supervisory relay for independently controlling the continuity of such signaling circuit.

24... In a telephonesystem, a plurality of telephone lines extending by their limbs from substations to an exchange, cord cir cuits at the exchangecfor connecting the lines for conversation,

plurality of their limbs exchange, cord cira signaling circuit adapted to be manually connected to such cord circuits, manual means associated with each of such cord circuits for controlling the continuity of the signaling circuit thereto, and a supervisory relay for independ ently controlling the continuity of such signaling circuit through normally closed con tacts operated by such relay.

25. In a telephone system a plurality of telephone lines extending by their limbs from substations to an exchange, cord cir cuits at the exchange for connecting the lines for conversation, a signaling circuit adapted to be manually connected to such cord circuits, manual means associated with each of such cord, circuits for controlling the continuity of the signaling circuit thereto, and a supervisory relay for independently controlling the continuity of such sig naling circuit, the energizing winding of such relay being independent of the signal ing circuit.

26. In a telephone system, a plurality of telephone lines extending by their limbs from substations to an exchange, cord circuits at the exchange for connecting the lines for conversation, a signaling circuitadapted to be manually connected to such cord circuits, and a non-marginal supervisory relay under the control of the called. substation for interrupting the continuity of the signaling circuit.

27. In a telephone system, a plurality of telephone lines extending by their limbs from substations to an exchange, cord circuits at the exchange for connecting the lines for conversation, a signaling circuit adapted to be manually connected to such cord circuits, and a non-marginal supervisory relay adapted to interru t the signaling circuit When the associate" cord circuit is connected to a busy line.

28. In a telephone system, a plurality of telephone lines extending by their limbs from substations to an exchange, cord circuits at the exchange for connecting the lines for conversation, a signaling circuit adapted to be manually connected to such cord circuits, and a relay the contacts of Which are in the signaling circuit, the energizing winding of such relay being in circuit with the connected line but not in such signaling circuit.

.29. In a telephone system, a plurality of telephone lines extending by their limbs from substations to an exchange, cord circuits at the exchange for connecting the lines for conversation. a signaling circuit adapted to be manually connected to such cord. circuits, and a relay the contacts of which are in the signaling circuit, the energizing Winding of such relay being connected to one of the talking strands of the associated cord circuit.

30. In a telephone system, a plurality of telephone lines extending by their limbs from substatio s to an exchange, cord circuits at the exclnnge for connecting the lines for conversation, a signaling circuit adapted to be manually connected to such cord circuits, and a supervisory relay for controlling the continuity of such signaling circuit to one of the cord circuits when such cord circuit is cmmectcd to one of the lines, such relay connected so as to be operated only by direct current.

31. In a telephone system, a plurality of telephone lines extending by their limbs from sul stations to an exchange, cord circuits at the exchange for connecting the lines for conversation, a signaling circuit adapted to be manually connected to such cord circuits, a first relay adapted to place a supervisory signal '1 condition to operate when the associated cord circuit is connected with one of the lines, and a second relay adapted to render such supervisory signal inoperative When the called subscriber responds. the cnergization of the first relay serving to close a break in the energizing circuit of the second relay and the encrgization of such second relay serving to interrupt the continuity of the signaling circuit to such cord circuit.

In a telephone system, a plurality of telephone lines extending by their limbs from substations to an cxcl'iange, cord circuits at the exchange for connecting the lines for cmiversation, a signaling circuit adapted to manuallybc connected to such cord circuits, a first relay connected-to one talking strand of one of the cord circuits, and a second relay connected to the other talking strand of such cord circuit, the energization of the first relay serving to close a break in the energizing circuit of the second relay and the energization of such second relay serving to interrupt the continuity of the signaling circuit to such cord circuit.

33. In a telephone system, a plurality of telephone lines extending by their limbs from substations to an exchange, cord circuits at the exchange for connecting the lines for conversation, a signaling circuit adapted to be connected to such cord circuits, a key associated With each of such cord circuits by which an exchange operator may complete the signaling circuit to the correspoinling cord circuit after such cord circuit has been connected with one of the lines in ringing condition, and a relay the contacts of which are in the signaling circuit, the energizing Winding of such relay being in circuit with the connected line but not in such signaling circuit.

34. In a telephone system, the combination with a cord circuit, of a rin ing key therefor, a supervisory relay, sai ringing key being connected with a strand of the normal contacts of cord circuit through substantially as desaid supervisory relay, scribed.

85. In a telephone system, the co1nbination with a cord circuit, of a ringing key therefor, having a plurality of contacts normally in series with a portion of a talking strand of the cord circuit, a supervisory relay having contacts in the circuit of said key, said relay being actuated during conversation to disconnect said series key contacts from the talking circuit, substantially as described.

Copies of this patent may be obtained for five cents each, by addressing the calling end of the 36. In a telephone system, the combina tion with a cord circuit, a ringing generator, a supervisory relay, the current from said generator being connected with the cord circuit through normally closed contacts of said relay, substantially as described.

In witness whereof, I hereunto subscribe my name this 9 day of March A. I). 1908. \VILLLUA'I IV. DEAN.

\Vitnesses F. L. CLARK, S. A. BEYLAND.

Commissioner of Patents,

Washington, D. 0." 

